CAIRO (REUTERS, AFP) - Islamic State in Iraq and Syria (ISIS) claimed responsibility for a suicide bombing in Pakistan that killed at least 70 people and wounded more than a hundred on Monday in an attack on mourners gathered at a hospital in Quetta, the group's Amaq news agency reported.

"A martyr from the Islamic State detonated his explosive belt at a gathering of justice ministry employees and Pakistani policemen in the city of Quetta," Amaq said.

The Pakistani Taliban faction Jamaat-ur-Ahrar has also claimed responsibility for the attack.

Both the United Nations and the United States have condemned the attack, with UN Secretary-General Ban Ki-moon saying it was "particularly appalling" that the suicide attack targeted a group of mourners.

The bomber struck a crowd of some 200 people gathered at the Civil Hospital in Quetta after the fatal shooting of a senior local lawyer earlier in the day.

At least 70 people died in the attack and more than 100 were wounded.

"The targeting of mourners at a civilian hospital makes the attack particularly appalling," said Ban's spokesman Farhan Haq.

Ban urged the Pakistani government to do its utmost to bring those behind the attack to justice.